Thanks!

I'd finally begun to conclude that myself but had not the knowledge to begin to possibly identify any further.

Two questions...
- How many (or range) stages / instars might these or typical dragonfly larva transition through before emerging?
- Might the mass of egg-like material nearby by mayfly eggs?

Due to what looked like all the algal growth, or natural simulation of same on the nymph, I took a blade of grass to give it a very light tough to make sure it was indeed alive, and it did move a couple times. Their was a Red-legged Frog with it's head just above the waterline an inch or two away, that rather unusually refused to submerged despite all of us grouped around. This was at the surface of a huge drain going into a large complex stormwater drainage and detention pond system, and normally, despite the pond only being about 8' across this time of year (the drain itself is about 7-7-1/2 feet across, with a rebar grate (about 4" spacing) at its surface, and typically there will be 2-5 large bullfrogs at the surface or sitting just at the edge of the water. It's the most confined space I've ever seen our three local frogs, American Bullfrog, Red-legged Frog, and Norhtern Pacific Tree (Chorus) Frog sometimes all present, despite the bullfrog happy to eat the other two, and the RL Frog willing to eat its smaller cousin as well. I believe that that bullfrog likely travels within the stormwater system to other locations from this point, via underwater piping, openings and a couple ponds that don;t dry up. It's a real dog-eat-dog (or frog-eat-frog) environment that might not the the most ideal for nymphs once they become rather noticeable.